More Polio Cases Now Caused by Vaccine Than by Wild Virus

Four African countries have reported new cases of polio linked to the oral vaccine, as global health numbers show there are now more children being paralyzed by viruses originating in vaccines than in the wild.

In a report late last week, the World Health Organization and partners noted nine new polio cases caused by the vaccine in Nigeria, Congo, Central African Republic and Angola. Seven countries elsewhere in Africa have similar outbreaks.

In rare cases, the live virus in oral polio vaccine can mutate into a form capable of sparking new outbreaks.

Donors last week pledged $2.6 billion to combat polio as part of an eradication initiative. In recent years, problems with the vaccine have plagued the program and numerous eradication deadlines have been missed.